Using GPS Receiver 1PPS Output to Verify Time Stamp Accuracy and Measure Propagation Delay
[摘要] A simple pulse overlay circuit using a logic OR gate was developed to overlay a precise leading edge 1 pulse per second time reference marker from a global positioning system receiver onto a non-return -to- zero-level pulse code modulation telemetry data stream to validate time stamp accuracy and measure propagation delay in telemetry equipment.A pulse overlay (PO) circuit was designed to produce a time reference marker within a pulse codemodulation (PCM) telemetry data stream that was recorded and analyzed to validate an IRIGStandard 106-17 Chapter 10 recorder’s time stamp accuracy [1]. A manufacturer of a newlypurchased Chapter 10 recorder claimed the time stamp accuracy to be better than 10 microseconds(μs) with only IRIG-B120 (IRIG-B) input and better than 1 μs with IRIG-B and one pulse persecond (1PPS) inputs. The PO circuit and a Chapter 10 recorder test setup were used to verify thevendor’s data-time synchronization claims and to justify infrastructure upgrade costs to connectadditional cables to each purchased recorder. The circuit was also used to measure the propagationdelay (PD) of a long distance Telemetry multiplexer/demultiplexer telecommunication systemwhich the manufacturer did not provide a PD specification.Using the one pulse per second time reference marker of the global positioning system receiverand the pulse overlay circuit to overlay the one pulse per second variable pulse width signal into apulse code modulation telemetry stream provided an excellent means to validate time stampaccuracy within a Chapter 10 recorder and to measure propagation delays within a normaltelemetry operating environment. The positive results from the Chapter 10 recorder tests validatedthe vendor’s claims and justified the implementation to add the one pulse per second signal to therange Chapter 10 recorders. The pulse overlay circuit and test setups defined in this paper caneasily be used to measure other telemetry equipment.
[发布日期] 2018-11-05 [发布机构]
[效力级别] [学科分类] 工程和技术（综合）
[关键词] GLOBAL POSITIONING SYSTEM;TELEMETRY;PULSE CODE MODULATION;STAMPING;PROPAGATION;DELAY;PULSE DURATION;ELECTRONIC EQUIPMENT TESTS;DATA FLOW ANALYSIS;CIRCUITS;TIME SIGNALS [时效性]
